Do the deceased own one-third of the property's debris, or does the property revert to all heirs, knowing that they purchased the land on which the property was built from their brothers, and that the property was built with a loan taken by one of the deceased?

The claim of a fictitious sale requires proof; otherwise, the land belongs to your father, uncle, and grandmother, and the share of whoever among them has passed away transfers to their heirs. This issue is a dispute and must be presented to the Sharia courts or discussed directly with scholars for verification.